It is already known that polyurethane (PUR) and polyureas (PU), in particular foams, can be converted by alcoholic decomposition into homogeneous polyol-containing liquids which are directly suited for making rigid foams of PUR. Various types have become known in this field, the following publications being here cited by way of example:
DE-OS 25 16 863, U.S. Pat. No. 3,109,824, U.S. Pat. No. 3,404,103, DE-OS 25 57 172, DE-PS 27 38 572 or DE-PS 37 02 495.
The known processes have in common that alcoholysis is carried out with a considerable excess of diols or polyols to decompose the polyurethanes to such a degree that homogeneous polyol mixtures are obtained whose viscosity is low enough to reuse them directly or in homogeneous mixtures with short-chain polyols for making rigid polyurethanes. Therefore, all of the products obtained in these methods have a high hydroxyl equivalent which limits their application to the production of rigid polyurethanes. The methods mainly differ from each other by special reaction conditions, catalysts and process techniques.
Products which are suited for the manufacture of flexible to semirigid foams with respect to their viscosities and hydroxyl equivalents could so far not be recovered from polyurethanes and polyureas by alcoholic decomposition. Likewise, products which can be reused for the renewed preparation of polyurethane-ureas could so far not be recovered from polyurethane-ureas by alcoholic decomposition. In particular, a practicable method which serves to decompose RIM (reaction-injection-molding) or R-RIM (reinforced-reaction-injection-molding) parts based on polyurethane-ureas used on a large scale in the automotive industry and which yields reusable products has so far not become known.